# Radiation-Induced Degradation of a Cold-Redundant DC/DC Converter Under Total Ionizing Dose Stress

## TL;DR

This study examines how radiation affects a cold-redundant DC/DC converter, finding that the auxiliary power supply is especially vulnerable to degradation.

## Contribution

The paper identifies critical degradation mechanisms in cold-redundant DC/DC converters under total ionizing dose stress.

## Key findings

- Main output voltage and conversion efficiency remain stable after irradiation.
- Auxiliary supply voltage and efficiency degrade significantly, reducing controller supply margin.
- Device-level measurements show a negative threshold voltage shift due to oxide-trapped charge effects.

## Abstract

This paper investigates the degradation characteristics of a DC/DC converter operating under cold redundancy conditions when subjected to total ionizing dose (TID) effects. An optimized RCC isolated auxiliary power supply circuit was evaluated through 60Co γ-ray irradiation up to 100 krad(Si) at dose rates of 3.89, 8.89, and 13.89 rad (Si)/s, with electrical characterizations performed at both the system level and the device level, focusing on the critical VDMOS transistors. The results indicate that the main output voltage and conversion efficiency remain essentially stable after irradiation, whereas the auxiliary supply voltage and efficiency degrade significantly, leading to a pronounced reduction in the controller supply margin. Device-level measurements reveal a negative threshold voltage shift of approximately 0.5–1.0 V with clear dose-rate dependence, while the subthreshold swing shows no obvious variation, suggesting that the degradation is primarily dominated by oxide-trapped charge effects. In addition, a substantial increase in drain current at low gate voltages is observed, which may further exacerbate restart risks under cold redundancy conditions. These findings demonstrate that the auxiliary power supply and startup margin constitute critical vulnerability points of cold-redundant DC/DC converters under TID stress and should therefore be primary targets for radiation-hardened design.